Characterization of mechanically sheared ethylene–propylene copolymers by high resolution NMR

✍ Scribed by Andrew C. Kolbert; Joseph G. Didier

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 159 KB
• Volume: 35
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19970915)35:12<1955::aid-polb10>3.0.co;2-0

✦ Synopsis

We report high-resolution solution-state NMR experiments on chain ends generated in ethylene-propylene copolymers by mechanical shearing in an extruder. The use of the higher resolution of the 13 C-NMR spectrum, in a two-dimensional 1 H-13 C chemical shift correlation experiment, has allowed the complete resolution and assignment of the olefinic chain-end region of the 1 H-NMR spectrum. Simultaneously, the assignments of the 13 C olefinic resonances, previously identified [A. C. Kolbert, J. G. Didier, and L. Xu, Macromolecules, 29, 8591 (1996)] are confirmed. An iterative method for calculating the average molecular weight, based on quantitative measurements of the olefinic 1 H-NMR peak intensities is introduced and these results are compared with measurements from 13 C-NMR and size exclusion chromatography and correlated to reduced viscosities.